Friction locked grating and other open grid structures



Sept. 30, 1969 L. NAGIN- 3,469,359

FRICTION LOCKED GRATING AND OTHER OPEN GRID STRUCTURES Filed July 15,1965 2 Sheets-Sheet l L n v 1 n n r n n n 3 L n 1| n I u n u L I u n n uu u I u u MA u 11 n u u u u ll ll [I II ll H A II I] u u' n 1] I -n u 11j Fig.1 2b 2c 20 2b r H r 2c K2 I I I 2 2 I l W |H% E d 2a I, I 3 91i2a. Fig.6.

. 2c 2 2 Hi 2c [I Zc Fig.4. 2c 4 4 2 4 4 I I l I I I M Fig.5.

INVENTOR.

LEON NAGIN pflggjmawu his ATTORNEYS United States Patent US. Cl. 52-177Claims ABSTRACT OF THE DISCLOSURE The invention is concerned with anopen grid or grating whose bearing bars are slotted to slidably receiveangularly disposed cross bars embodying an enlarged portion, which crossbars are subsequently rotated to final position and during rotation thesaid enlarged portions are deformed, locking the cross and bearing barsin assembled relation.

The present invention relates in general to open grid load bearingstructures and to lattice type structures as used both for decorativearchitectural and other purposes wherein rigidity. and self-supportingstrength are desirable. Such structures may be of ferrous andnon-ferrous metals. Non-ferrous metal structures of the type hereindescribed are generally lighter in weight than those of equal strengthmade of ferrous metals.

I Many attempts have previously been made to produce a friction lockedgrating which will remain in tight assembly under trafiic conditions.Much difficulty hase been encountered in attaining this result since thecross bars, under alternate application of load and release therefromtend to cut into their supporting surfaces on the bearing bars and inmoving relative thereto impair the initial friction lock.

Previous attempts to overcome this condition as by welding the bearingand cross bars together have not always been successful, particularly inlight-weight grating. The welding of aluminum requires special equipmentand is thus more expensive to fabricate and assemble, than are weldedferrous metal grating.

One object of the present invention is to provide novel forms offriction locked open grid load bearing structures and lattice typestructures for other purposes which are light in weight and which remainin tight assembly under all conditions of their intended use.

Another object of the invention is to provide an aluminum open gridgrating of the type described, wherein each cross bar is locked infrictional engagement to the bearing bars at a plurality of points alongthe length of each cross bar.

A further object of the invention is to provide a friction lockedreversible load bearing grating, embodying the principles of theinvention.

These and other objects of the invention will be made apparent from thefollowing specification and the drawing forming a part thereof wherein:

FIG. 1 shows a plan view of a section of grating embodying one form ofthe invention;

FIG. 2 shows a cross-section taken on lines 22 of FIG. 1, illustratingthe friction locked relation between the cross bar and the bearing barin final assembly;

FIG. 3 shows an enlarged plan view of a portion of the grating of FIG. 1illustrating a second friction lock between the bearing and cross barsadjacent the top of the bearing bar;

FIG. 4 shows a side elevation of a portion of a bearing bar illustratingthe slotted openings therein to receive the cross bars;

3,469,359 Patented Sept. 30, 1969 ice FIG. 5 shows a side elevation of aportion of a cross bar, illustrating the manner of notching the crossbar for rotation thereof into final assembled position;

FIGS. 6 and 7 show end elevations of alternate forms of a cross bar;

FIG. 8 shows in plan view a section of reversible grating embodying analternate form of my invention;

FIG. 9 shows in side elevation a portion of one form of bearing bar asemployed in a reversible grating of the invention and having the webthereof slotted to initially receive the cross-bars;

FIG. 10 shows an end elevation of the bearing bar of FIG. 9;

FIG. 11 shows in side elevation a portion of one form of cross bar to beemployed in a reversible grating embodying the invention;

FIG. 12 shows an end elevation of the cross bar of FIG. 11;

FIG. 13 shows a partial side elevation of the bearing bars of FIG. 9,illustrating the manner in which the cross bar is rotated to finalposition;

FIG. 14 shows a partial side elevation of a bearing bar as in FIG. 9with an alternate form of slots in the web thereof to receive the crossbar of FIG. 15 and illustrates consecutively a bearing bar slot, thecross bar as initially received in the bearing bar slot and the crossbar rotated to final position;

FIG. 15 shows an end elevation of the cross bar of FIG. 14; and

FIG. 16 shows a partial elevation of the cross bar of FIG. 15 with slotsin the cross bar to receive the bearing bar head portion when the crossbar is rotated to upright position.

Referring now in detail to FIGS. 1 to 5 of the drawings, the gratingcomprises a plurality of longitudinally disposed and transversely spacedbearing bars 1 or load carrying members, connected by cross bars 2. Asshown in FIGS. 2 and 3, the bearing bars 1 are preferably of rectangularcross section. Spaced longitudinally of bars 1 and intermediate thevertical marginal edges thereof, as shown in FIG. 3, are a plurality ofopenings 3 corresponding in shape to the shape of the cross bars 2. Theopenings 3 of the bearing bars are slightly larger than the cross barsto be received therein. Preferably the cross 'bars 2 are freely receivedin openings 3 with a minimum clearance. These openings 3 extend inspaced relation longitudinally of the bearing bar 1, preferablyalternately disposed, so that the cross bars are initially disposedhorizontally for insertion through openings 3 of successive bearing barsand thereafter are rotated as hereinafter discussed.

The cross bars 2 are preferably of a modified rectangular shape having abase portion 2a of greatest width and one side wall 2b sloping inwardlyfrom above the base portion, as shown in FIG. 2. The top and bottomlongitudinal edges and one side wall of cross bar 2 are preferably atright angles to each other. The height of the cross bar 2, when inerected position after rotation, brings its edge 26 preferably into theplane of the top edges of bearing bars 1. As best shown in FIG. 5, thecross bar 2 has rectangular slots 4 therein, of the same or slightlyless width than that of the thickness of the bearing bars. Such slots 4extend inwardly from the top edge 20 thereof to said rectangular baseportion and are spaced longitudinally of the cross bar for a purpose tobe herein dis cussed.

As best shown in FIGS. 2 and 3, the grating is assembled by threadingthe cross bars 2 horizontally through the aligned bearing bar slots 3.Each cross bar is thus alternately disposed relative to the nextsucceeding cross bar inwardly of the bearing bar, whereby each crossbar, in rotating to erect position, is rotated in an opposite directionrelative to each preceding and succeeding cross bar. By reason of theslots 4 of the cross bars being of equal or less width than thethickness of the unslotted bearing bar portions, the unslotted cross barportions between adjacent girder bars are deflected slightly duringrotation and frictionally engage the adjacent girder bar portions.

During this same substantially 90 rotation of the cross bars relative tothe bearing bars, the substantially square thicker base portion of thecross bar rotates within the slightly enlarged correspondingly shapedbearing bar slotted portions. Since such slotted bearing bar portionsare only slightly larger than the cross bar base portion, the latter isdeformed during this rotation and provides a strong frictionalinterlocking of the contacting surfaces. To facilitate deformation ofone of the contacting surfaces, the cross bars may, but not necessarily,be formed of a softer metal than that forming the bearing bars.

Due to the foregoing rotation of the cross bars 2 relative to thebearing bars 1, the slotted portions 4 of the cross bars are indeflected frictional locking engagement with the adjacent unslottedportions of the bearing bars 1. As a result, portions of each cross bar2 are locked into frictional engagement with the adjacent slotted andnonslotted areas of the bearing bars 1. Additionally the broad base 2aof the cross bars is in bearing engagement with the slotted portion ofthe bearer bars resisting penetration of the loaded cross bars into theunderlying bearing bar portions.

It will be understood that alternate forms of suitable bearing and crossbars may be employed. It is desirable to have the cross bar base portionof greater cross-sectional area than that of the bearing bar, ashereinbefore stated. Cross sections of two alternate forms of cross barare shown in FIGS. 6 and 7 of the drawing. It will be understood that inall cases the bearing bar slots will conform, in shape, to the cross barto be freely received therein.

Referring now to FIGS. 8 to 13 of the drawing, wherein is shown amodification of the invention, the grating hereinafter disclosed isreferred to as a reversible grating. That is, either planar face of thegrating may be the load receiving surface and the grating may beinverted when desired.

As shown in FIG. 9, the bearing bars 101 are symmetrical about theirlongitudinal centerline or neutral axis. Such bars '101 may be of anydesired contour and may be an extruded or rolled member.

Bearer bars 101, as shown, preferably comprise an aluminum extrusionhaving thickened top and bottom portions 102 connected by anintermediate web portion 103, of lesser thickness. Such bars, of course,may if desired be of uniform thickness throughout the vertical heightthereof. The outer faces 102a of the bars 101 may have suitablecorrugations therein, as indicated, to provide a non-skid surface.Spaced longitudinally of bearing bars 101 are suitable apertures orslots 104 to receive cross bars 105. Such slots 104 are slightly largerthan the cross bars to be received therein so as to facilitate threadingthe cross bars 105 therethrough. The cross bars, as shown in FIG. 12,have a thickened intermediate portion and, as indicated by thelongitudinal neutral axis x of the bar, this enlarged portion of slot104 is preferably equally spaced about said neutral axis.

Cross bars 105, as shown in FIGS. 11 and 12, are of a modified T-shape,having an elongated top portion 105a. and a substantially rectangularmid-portion 105b of greater thickness than said top portion 10511. Theportion 105a, at opposite ends of mid-portion 105b, is provided withinwardly extending suitably shaped slots 105c therein conforming to theshape of the bearing bar portions to be received therein, as hereinafterdiscussed. The respective widths of slot portions 105c in the cross barsare preferably that of the corresponding portions of the bearing bar 101to be engaged thereby.

Referring now to FIGS. 9 and 13, after the bearing bars 101 and crossbars 105 have been slotted, as above described, the cross bars 105initially disposed in a horizontal position are freely threaded throughthe corresponding bearing bar slots 104 of FIG. 9. Thereafter each ofthe cross bars 105 are rotated through an angle of substantially intothe position as best shown in FIG. 13. By reason of the cross barinitially conforming to the shape of the slots 104 in the bearing barand being only slightly smaller than the adjacent bearing bar slotportions, the cross bar portions 10511 must deform during rotation fromhorizontal to vertical position. To facilitate such deformation, therolled or extruded aluminum cross bars 105 may, but not necessarily, bemade of a softer alloy than that from which the bearing bars are made.During such deformation of cross bar portions 105b, a strong frictionlocking effect is established at this portion of the intersection of thebearing and cross bars.

The slotted upper and lower portions 105c of the cross bars 105, beingsubstantially of the same dimensions as that of the bearing bar portionsto be engaged thereby, may also deflect or distort during the aforesaidrotation. This deflection or distortion would provide a strongfrictional locking engagement at the respective areas of contact as thecross bars move into vertical position. As a result thereof each of thecross bars, at each area of engagement with the several bearing bars,effects a strong frictional locking engagement for substantially thefull vertical height of the cross bar. If desired, the cross bars, beingsymmetrical about the mid-portion 105c thereof, may be alternatelyrotated clockwise or counter-clockwise upwardly from horizontal tovertical position, about such mid-portion 105b as previously describedin connection with FIG. 2 of the drawing.

A further modification of the invention is shown in FIGS. 14, 15 and 16of the drawings. Here the longitudinally extending bearing bars 201comprise enlarged head portions 202 at opposite longitudinal edges of aweb portion 203. Each head portion 202 may have a grooved face 202asimilar to that shown at 102a of FIG. 10. Such shaped members aresometimes referred to as I-bars.

The cross bars 205, as shown in FIG. 15, are comprised of asubstantially square or rectangular base portion 206 and an upstandingthinner portion 207. Portions 207, above the base portion 206, as shownin FIG. 16, has suitable slots 205a therein to receive the web 203 andone head portion 202 of the bearing bar 201. The base portion 206 of thecross bar at one or more sides thereof may be provided withindentations, such as 208 extending the length thereof. These latterindentations facilitate deformation of portion 206 during movement frominitial to final position as illustrated in FIG. 14.

As shown in FIG. 14, the web 203 of the bearing bar 201 is slotted at204 to freely receive the cross bars 205. Slots 204, instead of beinghorizontally disposed as at 104 in FIG. 9, are disposed substantially at45 to the horizontal centerline of each bearing bar 201. Slots 204 arepreferably of such size as to permit freely threading the cross bartherethrough, but with a minimum of clearance. For purposes ofillustration, FIG. 14, at A shows the slotted opening 204 only, at B isshown slot 204 with a bearing bar 205 mounted therein, and at C is shownslot 204 with the bearing bar 205 rotated to vertical position. As willbe noted upon comparison of B and C, the indentations 208 facilitatedeformation of the cross bar base portion 206 in moving from position Bto final assembled position C.

Having disclosed and described several species of the invention, it willbe apparent that the longitudinal or bearing bars may be of a pluralityof different shapes, as may also the connecting cross bars.Additionally, the herein described methods of assembly may be employedto provide other forms of assemblies in addition to gratings, such aslattice type structures.

The friction lock between the enlarged portions of the cross bars andthe webs of the longitudinal bars is obtainable from a variety ofshapes, provided only that one or the other or both are partiallydistorted during movement relative to each other. Thus the cross barsmay be friction locked only at their intersection with the longitudinalbars, or as shown in FIG. 13, a cross bar may have two frictionallocking engagements with each longitudinal bar.

When non-ferrous metals are employed in the longitudinal and cross bars,I have found that many suitable alloys may be employed, depending uponthe end use of the completed structures. In the case of aluminum, manyof the alloys may be employed in both longitudinal and cross bars. Ifdesired, and the conditions of use permit, a softer alloy may beemployed in one of the intersecting bars to facilitate assembly.

I claim:

1. In a grating, the combination of,

(a) a plurality of longitudinally disposed transversely spacedrectangularly shaped bearing bars, each having a depth greater than thethickness thereof and each bar provided with a plurality oflongitudinally extending spaced slotted openings therethrough forreception of cross bars extending between a plurality of said bearingbars,

(b) each said beairng bar slotted openings being of sufficientdimensions to freely receive the cross bar disposed therethrough andconforming to the contour of said cross bar being initially disposedtherein,

(c) a plurality of transversely disposed cross bars spacedlongitudinally of said bearing bars within said slotted openings thereofand each comprising a longitudinal disposed angularly shapedintermediate portion of maximum thickness with portions of lesserthickness extending laterally from opposite margins thereof, and

(d) slotted openings in said laterally extending cross bar portions ateach side of said cross bar intermediate portion for embracing the upperand lower marginal portions of the bearing bars during rotation of thecross bar mid-portions into frictional locking engagement with saidbearing bar slotted openings.

2. The grating as defined in claim 1, wherein said cross bar angularlyshaped intermediate portions, when initially mounted in said bearing barslots, extends above and below the neutral axis of said bearing bars.

3. The grating as defined in claim 1, wherein said hearing bar has itslongitudinal marginal portions of greater thickness than the slottedconnecting web portion receiving said cross bars.

4. The grating as defined in claim 3 wherein the exposed faces of saidbearing bar longitudinal marginal portions are serrated to provide anon-skid surface.

5. In an open grid structure of the character described,

the combination of (a) a plurality of longitudinally disposed andtransversely spaced bearing bars each having a depth greater than thethickness thereof and each having a plurality of longitudinally spacedslotted openings therethrough for reception of cross bars extendingtransversely thereof,

(b) each cross bar opening being of suflicient dimensions to slidablyreceive a cross bar being threaded therethrough at an angle to thevertical axis of the bearing bar and including a rectangular shapedportion, slidably receiving a correspondingly shaped portion of saidcross bar,

(c) a plurality of transversely disposed cross bars each extendablethrough a plurality of the transversely aligned slots in saidlongitudinally disposed bars into fully threaded position relativethereto,

(d) each said cross bar having an enlarged portion thereon in spacedrelation to at least one longitudinal edge of the 'bar and whichcorresponds in shape to said bearing bar rectangularly shaped openingand having a plurality of slotted openings therein extending from saidlongitudinal edge to said enlarged portion and in registry with adjacentareas of the bearing bar when the threaded cross-bar is in said fullythreaded position so that each said cross bar may be rotated about itslongitudinal axis from said full threaded position to a final positionangularly displaced therefrom, and

(e) said cross bar enlarged portion being so dimensioned relative to thecorresponding opening in said bearing bar that it will be permanentlydistorted by the bounds of said opening in the course of such rotation.

References Cited UNITED STATES PATENTS 1,132,021 3/1915 Mark et al.52667 1,426,736 8/1922 Hess 52-667 2,287,558 6/1942 Nagin 52-667 FOREIGNPATENTS 810,856 1/1937 France. 1,007,873 2/ 1952 France.

FRANK L. ABBOTT, Primary Examiner PRICE C. FAW, JR., Assistant ExaminerUS. Cl. X.R. 52-667; 669

